i think my water pump is broken

[Ricky Twine]

hiya guys..... VW sharan, 1999, 1.9tdi

my problem is as follows.......

drove to london a week ago, was fine, on the return home journey (to poole, dorset) it over heated, had to pull over a few times and had to have heaters on full on hot or it would overheat super quick.. i was assuming it was the head gasket.

so toay i was working on the brakes on my sisters 1.9tdi 1997 galaxy, we swapped over the servo/master cylinder to fix her car, and when i took of the engine undercover from my sharan to collect a bolt i dropped, i noticed there was a leak on the left of the engine from where the auxillery belt is, my dad took off the water resivour cap and BOOM! the system emptied right in front of me rather quickly leaving a mess all over the floor, all from the same spot it was leaking, i removed the tray completely, and had a feel around, and one of the cogs was lose, i mean it wiggles side to side and it should have a 1cm gap or so from the other cog, and theyre touching, there is also water comming from the same spot as that cog, but from behind it.... i will attach a picture from a ebay add i found with the same engine to show what cog i mean.
i think its the water pump but im not sure

[attachimg=1 align=left width=400]

also, i few months back i had the change the auxillery belt because it snapped, so i had the remove the small belt attached to the faulty cog to gain access, im wondering if i over tightend this one with the teethes sproket tensioner thing on the bottom which has caused the problem?

thanks in advance, Ricky

[Chrispb]

Yes that is the water pump